1. Field of the Invention
The present invention relates to optical sights. More specifically, the present invention relates to systems and methods for illuminating a reticle in an optical sight.
2. Description of the Related Art
An optical sight (e.g., a gunsight or scope) is used to accurately aim a device such as a firearm, crossbow, or camera. A conventional optical sight uses a lens system that provides a magnified image of a target for viewing by an observer (the shooter), and typically includes a reticle, which is a pattern (crosshair, circles, dots, etc.) superimposed over the target image that is used by the observer to align the device.
Reticles often need to be illuminated. Optical sights for military applications often use a radioactive light source, such as tritium, for illuminating the reticle. Tritium light, however, is dim, making it suitable for nighttime operation but not for daytime use. LED light sources can provide brighter illumination of the reticle, but LEDs typically require a battery that needs to be frequently replaced, and which may fail at an inopportune time.
Fluorescent fibers or light pipes are another source for providing daytime illumination. A fluorescent fiber absorbs ambient light (e.g., daylight) and converts it to a bright fluorescent beam, which is used to illuminate the reticle. A fiber can provide daytime reticle illumination without the need for an external power source, but will not work under conditions of low ambient light (e.g., at night).
An optical sight capable of both day and night time use, which does not require an external power source, is highly desirable, especially for use in military applications. No single light source, however, is optimal for both conditions. A solution would be to include multiple illumination sources in the sight: a source suitable for daytime operation, such as a fluorescent fiber, and a source suitable for nighttime operation, such as tritium. The limited space and optical geometry of a typical sight, however, can make it very difficult to couple light from different sources to efficiently illuminate the reticle.
Hence, a need exists in the art for an improved system or method for coupling light from multiple sources to illuminate a reticle in an optical sight.